-54- 



without encountering a single fishing boat, while anglers were always in 

 evidence at Upper Spavinawo 



The census figures above are not believed to show as much difference as 

 may really exist since the checks on Upper Spavinaw missed several periods 

 when outstanding catches were made. For example, Mr. Sam Jackson, biologist 

 for the City of Tulsa, estimated the largemouth bass catch by fishermen using 

 rental boats in the period from mid-August to mid-September of 1953 to have 

 been 14,000 legal-sized bass. His figures did not include bank fishing or 

 private boat fishing. This was \mdoubtedly a peak period, but it is doubtful 

 if 14,000 legal bass have been harvested from Heyburn since its impoundment. 



DISCUSSION 



Soil turbidity has been evaluated here as a principal limiting factor 

 in growth and reproduction of fishes, food production and fishing success. 

 Turbidity was studied because it is the most obvious and readily measured of 

 the various effects of erosion. It should be mentioned, however, that tur- 

 bidity may be only the visible evidence of other unmeasured factors which 

 either contribute to, or are associated with, the undesirable conditions 

 common to turbid waters. As observed by Irwin (1945), permanently turbid 

 waters are invariably low in organic fertility. This presents the question 

 as to whether turbidity is the cause or the result of the low fertility. In 

 reality, it may be both. All waters are turbid following a large infliuc of 

 erosion silt. The rate and degree of clearing depends upon the nature and 

 size of the injected soil particles and the organic fertility of the water. 

 Other conditions being equal, the most fertile water will clear more rapidly. 

 This is due to a higher availability of positive ions capable of neutralizing 



